Code
C1993
LAND ROVER
C — Chassis
Pressure sensor - circuit failure
Views:
UK: 4
EN: 6
RU: 2
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the sensor circuit
- Corroded, loose or damaged connector or terminal
- Faulty pressure sensor
- Poor or missing ground or reference supply to the sensor
- Water ingress or contamination at the sensor/connector
- Blown fuse or intermittent power supply
Symptoms
- Warning lamp(s) illuminated (ABS, suspension, traction, or general fault light)
- Associated system disabled or degraded (ABS, ESP, adaptive suspension, fuel pressure control)
- Recorded C1993 stored in fault memory with freeze frame data
- Erratic gauge or live data readings for pressure (stuck, zero, or out-of-range values)
- Intermittent faults or faults that return after repair attempts
What to check
- Read DTCs and freeze frame data with a capable scan tool; record related codes
- Confirm which system the sensor belongs to (ABS, suspension, fuel, etc.) and identify sensor wiring colors/pinout from a wiring diagram
- Visually inspect the sensor, connector and wiring for damage, corrosion, heat or fluid contamination
- With ignition on (engine off), backprobe the sensor connector and verify reference supply (usually 5 V or system supply), signal voltage, and ground presence
- Check signal while changing system pressure (or simulate pressure if safe) and observe live data for sensible changes
- Perform wiggle test on harness and connector while monitoring live data to catch intermittent faults
Signal parameters
- Most pressure sensors are analog and use a reference supply (commonly 5 V) with a 0–5 V signal proportional to pressure
- Typical usable signal range ~0.5–4.5 V (varies by sensor); at zero or low pressure the voltage is near the low end, increasing with pressure
- Some sensors are resistive or frequency-output types—consult model wiring/tech data before assuming voltage type
- Sensor ground should be close to 0 V; reference supply should be stable within ±10% of specification
- If CAN or serial digital sensor, expect digital data packets instead of analog voltage; use manufacturer-specific tool for diagnostics
Diagnostic algorithm
- Safety: Park vehicle on level ground, chock wheels, switch off engine. Relieve system pressure if working on hydraulic/air lines per service manual.
- Scan tool: Read and record DTCs, freeze frame and live data. Note which pressure sensor and circuit are referenced.
- Visual inspection: Examine sensor, connector and wiring for obvious damage, corrosion, fluid ingress or poorly seated connectors.
- Identify wiring: Use wiring diagram to identify reference, signal and ground pins at sensor and module.
- Power & ground verification: With ignition ON, backprobe connector. Verify reference voltage (typically 5 V), ground continuity to chassis, and that supply voltage is present and correct.
- Signal check: Observe live signal voltage while varying system pressure (by operating pump or applying pressure safely). Confirm voltage moves smoothly and within expected range. If signal is fixed or out-of-range, suspect wiring or sensor.
- Continuity/short checks: With ignition OFF, measure resistance/continuity from sensor pins to the control module pins and to ground/battery to check for opens or shorts to power/ground.
- Wiggle/test under load: Start engine (if safe) or operate system and wiggle harness/connector to reveal intermittent faults. Monitor live data and DTC behavior.
- Component substitution: If wiring and supplies are correct but signal is bad, replace the pressure sensor with a known-good unit and retest.
- Module check: If new sensor and good wiring still produce C1993, inspect/control module input circuit and consult manufacturer for module bench test or replacement procedures.
- Clear codes and test-drive or operate system to confirm repair and that code does not return.
Likely causes
- Open or damaged wiring or pinched harness (most common)
- Corroded or loose connector terminals
- Failed pressure sensor element
- Poor ground or missing reference supply
- Water ingress or physical damage to sensor
- Control module fault (least likely)
Fault status
Status
C1993 — Pressure sensor circuit failure detected. Check sensor, wiring and supply. Refer to diagnostic procedure.
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.0 hours
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